There is a continuous demand in the automotive, heavy duty, and chemical industry for high performance elastomers that have improved resistance to aggressive oils and fuels. Hydrogenated nitrile butadiene rubber (HNBR) is a high performance specialty elastomer used in a variety of demanding engineering applications: automotive, chemical and heavy duty industries, oil well exploration, and mining. HNBR, is made by the selective hydrogenation of the double bonds in nitrile rubber. It has a combination of unique properties: high tensile strength and very good mechanical properties even at elevated temperatures, excellent abrasion resistance, low compression set, excellent heat resistance, very good resistance to ozone, weathering, and high energy radiation, low permeability to vapors and gases. In addition, HNBR has very good resistance to oils, fluids, diesel, fuels, sour gasoline, lubricating oils with aggressive alkaline additives, as well as good resistance to crude oil even in the presence of hydrogen sulfide, amines, and corrosion inhibitors.
U.S. Pat. Nos. 7,381,781; 6,841,623; and 6,780,939 assigned to LANXESS recently introduced to the rubber industry a novel HNBR technology that enables the production of low viscosity HNBR polymers, previously commercially impossible to manufacture. The commercial product is sold by LANXESS under the trade name THERBAN® Advanced Technology (AT). These low Mooney viscosity HNBR grades have several benefits over standard HNBR products, including: retention of physical properties known for HNBR polymer plus the added benefit of improved processability; combined with a narrow molecular weight distribution to maintain excellent mechanical properties; faster black incorporation time and lower mix temperature; faster mold filling and shorter cycle times in injection molding; faster output and compounds of smoother surfaces and sharper edges are obtained in extrusion; lower compound costs by using higher fillers levels.
The present invention provides novel HNBR compositions that have very high filler levels resulting in very good mechanical properties, processability, and especially excellent resistance and minimal swelling in fluids known to be aggressive to nitrile polymers such as methyl ethyl ketone (MEK), toluene, and certain fuels. Such compositions and their properties are not known in the art.